以NaBrO_3/H_2SO_4氧化体系合成己二酰-1,′6′一双(4-卤偶氮苯)

取代酰肼化合物是制备偶氮化合物的原料,是一种非常重要的有机化合物,具有广泛的应用价值。它可以和金属形成稳定络合物,对聚烯烃等高分子材料的“铜害”有良好的防护,因而在电线、电缆、钢丝、轮胎等与铜及其它重金属相接触的高分子工业制品中得到广泛应用,被称为金属减活剂[2     

POLYMER-PLATINUM COMPLEX CATALYSTS FOR OXIDATION OF METHANOL TO FORMALDEHYDE

Two kinds of polymer-platinum complexes: silica-supported poly-γ-diphenylphosphinopropylsiloxane-platinum complex and silica-supported polyphenylsilazane-platinum complex, have been found very active and selective in catalyzation of oxidation of methanol to formaldehyde at room temperature and under an atmospheric oxygen pressure. Their catalytic activities are greatly affected by P or N/Pt gram atomic ratio.     

RECOGNITION SEQUENCE SPECIFICITY OF SIGNAL PEPTIDASE I AND THE ROLE OF SIGNAL PEPTIDE IN SECRETION OF PROTEIN IN Bacillus subtilis

By recombinant DNA technology, the N-terminal of the β-protein encoding region of plasmid pUBHO is fused with the structure gene of α-amylase from Bacillus licheniformis. This gene fusion is called βAmy. It is able to transcribe and translate in phase. Protein fusion can be secreted into the medium mediated by β-signal peptide. The efficiency of secretion is about 10% of the synthesized pre-α-amylase. By comparing the secretion capacities and analysing the restriction sites on β-Amy genes and the molecular weights of the mature α-amylase secreted by B. subtilis harbouring different plasmids, it is indicated in vivo that the recognition and cleavage sequence for signal peptidase I of B. subtilis is Ala-Ala-Ala Ala. The results also indicate that the secretion of the α-amylase in B. subtilis is in accordance with the post-translational transportation mode.     

四氢键二聚体和分子组装

介绍了最近几年新的四氢键有机二聚体研究的进展及其在分子自组装和分子聚 集体化学研究中的应用。     

泡沫铅对VRLA电池负极活性物质结构及性能影响

0引言随着36V/42V汽车电源系统的提出,新一轮汽车用电池的竞争不断加剧。从目前情况看,铅酸电池由于具有成本低廉,使用可靠,原材料来源丰富,铅回收率可高达98%等优点,因此成为电动车电源最实际的选择之一[1]。但作为电动车用电池,需要克服其比能量低、充电接受能力差和负极硫酸盐化等缺点。为此各国科学家开展了大量的研究工作。最近报道用铸造多孔体作为敞口铅酸电池的集流体,它的比表面积为14cm2·cm-3,正极活性物质利用率上升到50%,远高于传统的铸造板栅[2]。在铅酸电池集流体研究领域里另一个重大进步,就是以R V C(R etic-ulated V i…     

滂胺天蓝-氨基糖苷类抗生素的显色反应及其分析应用

在 pH2.0～7.0的条件下 ,滂胺天蓝(PSB)与硫酸卡那霉素(KANA)、硫酸庆大霉素(GEN)和硫酸新霉素(NEO)等氨基糖苷类抗生素反应生成蓝色离子缔合物 ,最大显色波长位于686～690nm ,线性范围分别为0～14.0、0～12.5、0～14.0mg/L ,摩尔吸光系数(ε)分别为1.53×104、1.12×104、1.47×104L/(mol·cm) ;最大褪色波长位于620～622nm ,线性范围分别为0～14.0、0～12.0、0～14.0mg/L ,摩尔吸光系数(ε)分别为1.41×104、1.43×104、2.42×104L/(mol·cm) ;当用双波长叠加法测定时 ,ε值分别为2.94×104、2.55×104、3.89×104L/(mol·cm) ;探讨了适宜的反应条件 ;该法用于市售药物中氨基糖苷类抗生素含量的测定 ,结果令人满意     

Michael Addition of Thiols to á,(a)-Unsaturated Carbonyl Compounds Catalyzed by Bifunctional Organocatalysts:Asymmetric Michael Addition and Asymmetric Protonation

Recently the hydrogen-bond activated reactions have attracted much attention.1 Takemoto2 reported a highly enantioselective Michael addition of manolate to nitroolefins catalyzed by a bifunctional organocatalyst with tertiary amine and thiourea moiety. As we known,stereoselective conjugate additions of thiols are interesting due to the standpoint of biological and synthetic importance, however, only very limited good results have been obtained except for the works of Shibasaki3, Kanemasa4 and Deng5 et al.In this letter, we report an efficient catalytic asymmetric Michael reactions of thiols to a,a-unsaturated carbonyl compounds promoted by bifunctional organocatalysts. A series of organocatalysts with chiral amine and thiourea structures were designed and synthesized and have been successfully applied in the conjugated additions of thiols to a,a-unsaturated imides and enones.The reactions got quantitative yields and the ee values were up to 84%. It is noteworthy that the a-asymmetric protonation (up to 43% ee) also could be achieved.The Michael addition between aromatic thiols and a,a-unsaturated carbonyl compounds isdescribed as follows:Works to further increase the enantioselectivity is under investigation in our laboratory.     

钯催化α-炔醇立体专一合成α-（Z）-氯亚甲基-β-内酯

首次在一氧化碳存在下，以仲丁醇和苯为混合反应溶剂，氯化钯和氯化铜为催 化体系催化α-炔醇羰基化，立体专一合成α-（Z）-氯亚甲基-β-内酯环。     

冠醚化二苯甲酮的合成及其光物理行为

本文报道采用在多聚磷酸中酰化的方法,合成了冠醚化二苯甲酮1～8。它们与叔胺类共用可能被用作光引发剂。为此,用紫外光谱详细研究了这些化合物及其络合后的光物理行为。还提及化合物3和4作为紫外吸收剂的可能性。     

碳纳米管的共价修饰

碳纳米管(carbon nanotubes, CNTs)的溶解性和分散性较差是目前制约其广泛应用及在一些有特殊要求的领域(如生物技术)应用的主要原因之一. 对CNTs进行共价修饰是改善其溶解性和分散性的有效方法之一. 目前CNTs的共价修饰主要通过两类反应来实现: 羧基的衍生反应和直接加成反应. 介绍了基于这两种反应的几种共价修饰方法, 比较了各种修饰方法的优缺点及其对CNTs的溶解性和分散性的改善效果.